1. Field of the Invention
The present invention relates to a chucking device, a motor, a disk drive apparatus and a chucking device manufacturing method.
2. Description of the Related Art
A disk drive apparatus such as an optical disk drive or the like is equipped with a brushless motor for rotating a disk. The brushless motor includes a chucking device that rotates together with a rotary unit. The chucking device is capable of holding a disk in place. The disk drive apparatus can rotate the disk by driving the brushless motor while holding the disk in place with the chucking device.
In recent years, the rotation speed of a brushless motor tends to become higher along with the increase in the operation speed of the disk drive apparatus. As the rotation speed of the brushless motor gets increased, a vibration problem is likely to occur. One of the causes of brushless motor vibration is the eccentricity in the gravity center of a disk. The disk gravity center suffers from individual variability and differs from disk to disk. The vibration problem is apt to occur if the gravity center of the rotary unit of the brushless motor and the disk as a whole does not coincide with the rotation center of the rotary unit.
In case where a plurality of rolling balls is arranged along the circumferential direction of the rotary unit, noises are generated due to the rolling movement of the balls. The noises attributable to the rolling movement of the balls are highly likely to generate during acceleration and deceleration of the brushless motor and after stoppage thereof. In order to reduce such noises, it is thinkable, for example, to attach shock-absorbing materials to the surfaces of the rotary unit with which the balls make contact. If the shock-absorbing materials are attached to all the surfaces with which the balls make contact, the resistance to the balls becomes greater. This may hinder the smooth rolling movement of the balls.